1. Field of the Invention
The present invention relates to soft touch polyolefin compositions and a method of making such soft touch polyolefin compositions, and in particular, soft touch polyolefin compositions that include cross-linked or uncross-linked ethylene-propylene thermoplastic elastomers.
2. Background Art
Thermoplastic polyolefins (“TPO”) resins are blends of polypropylene and elastomers. In many applications, TPO resins may include such additives as pigments, antioxidants, stabilizers, and fillers. They can be made by physically blending in an internal mixer, or by polymerizing in a reactor. TPO resins are useful in a number of molding processes, which include, for example, blow molding, injection molding, thermoforming, blown film extrusion, cast film extrusion, sheet extrusion, profile extrusion, and the like. Moreover, TPO resins are used to form a variety of items ranging from automotive components to plastic films to containers.
Each year, polymeric resins are used to form a multitude of plastic containers and storage bottles. In particular, the personal care industry distributes a significant portion of its products in plastic bottles (i.e., shampoo, lotions, and the like.) Furthermore, in the automotive industry, TPO resins are increasingly being used to form interior components. Presently, there is a trend to improve the aesthetics of such containers by improving the tactile softness of these containers when they are held by the user. Similarly, the automotive industry requires that many interior components have an aesthetically pleasing soft touch. The sensation of “softness” tends to be somewhat subjective, without a clear correlation to any particular physical property. However, properties which quantify stiffness and hardness such as the flexural modulus and Shore A hardness relate somewhat to softness and are useful in developing such materials. Currently, there has only been limited success in developing containers formed from polymeric resins that possess the requisite “softness.”
Accordingly, there is a need in the prior art to develop polymeric resins, and in particular, TPO resins that will improve softness when touched by the end user. Moreover, such resins should be formed by processes that are economical and relatively easy to implement.